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Testing Chinese Tubes


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#1 Henry the Hermit

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Posted 24 December 2011 - 12:57 PM


I've owned a Dankung Jungle Hunter II for more than a year. Right up front, I'll say I don't like the Dankung, but I do like the thin Chinese tubes. I plan to test a variety of configurations, and will use the Dankung because of the ease of changing tubes. To kick things off, here are the results I got from the original OEM bandset, which I assume were 1745.

Pull weight at 30 inches - 19 pounds
Velocity -
.375 lead ball (75 grains) - 192 fps avg 5 shots
.429 lead ball (115) grains - 182 fps avg 5 shots
.495 lead ball (175 grains) - 161 fps avg 5 shots
Note: all measurements were made with my computer and Audacity. Later I will compare the computer measurements against my Chrony.
* Velocity measured at my normal 34 inches draw.

Further testing will be with 1842 because that is what I have.

Now I'm going outside to make some Chrony measurements.

#2 Henry the Hermit

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Posted 24 December 2011 - 02:30 PM

I just spent an enjoyable hour shooting and recording Chrony readings.

The first step was to measure a Cholita with #107s to see how close the Chrony is to my previous computer measurements. I got a 5 shot average with .375 lead of 185.4 fps vs 178.7 with the computer, a difference that could easily be caused by warmer weather or a slighter longer draw. Close enough.

Then I compared my older Lee mold ammo against the newer (and slighter smaller Do-It mold ammo. The Lee balls measure .375 and weigh 75 grains, the Do-It balls are .364 and weigh 71 grains. Using 1842 tubes cut to OEM length with a Jim Harris pouch on the Dankung frame, the Lees averaged 212 fps and the Do-Its averaged 212.4 fps.

Next I shot a round with Do-It .31 cal. (actual diameter .304, weight 40 grains) for a 5 round average of 235 fps.

Having already measured the 3/8 inch balls, next up was .429 lead, calculated weight 115 grains. They zipped in at 202 fps.

Finally to round out the doubled 1842 tests I shot .495 balls, calculated weight 175 grains for a 5 round average of 184.4 fps.

Next up, some surprising results with "tapered" single 1842 tubes.

#3 Charles

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Posted 24 December 2011 - 02:48 PM

Nice results!!! Keep 'em coming.

Cheers ..... Charles
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#4 Henry the Hermit

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Posted 25 December 2011 - 09:37 AM

Just a teaser. I took a few shots this morning (OK, about 50), and with lightweight ammo, I am confident of hitting 300+ fps with Chinese 1842 tubes. I'm averaging 285 fps and one shot went 293 with .25 cal (6.35mm) steel. I'm hitting 260+ with .30 lead.

#5 Charles

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Posted 25 December 2011 - 10:29 AM

Impressive results with that lead. Will be interested to see what setup you are using.

Have a great Christmas.

Cheers ........ Charles
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#6 timdix

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Posted 25 December 2011 - 06:28 PM

I'm pleased to see those readings with 1842. I'm waiting for some Dankung 1842 to arrive for a round of testing myself.
Can I suggest you try a mixed set up: double 1842 fork side and single at the pouch side using the longest draw possible. I'd be very interested to see your results.
My tests with 1745 with a mixed set up rival taper flats! The draw however is almost a tad heavy for 3/8 steel.
I suspect 1842 with 3/8 using this setup would be ideal:easy draw,300fps speeds,shot count well into the hundreds. The real kicker is that the tubes are so easy to cut and change not to mention cheap(if you're just changing the single strand component).

Edited by timdix, 26 December 2011 - 08:21 PM.


#7 Rayshot

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Posted 25 December 2011 - 08:09 PM

I've owned a Dankung Jungle Hunter II for more than a year. Right up front, I'll say I don't like the Dankung, but I do like the thin Chinese tubes. I plan to test a variety of configurations, and will use the Dankung because of the ease of changing tubes. To kick things off, here are the results I got from the original OEM bandset, which I assume were 1745.

Pull weight at 30 inches - 19 pounds
Velocity -
.375 lead ball (75 grains) - 192 fps avg 5 shots
.429 lead ball (115) grains - 182 fps avg 5 shots
.495 lead ball (175 grains) - 161 fps avg 5 shots
Note: all measurements were made with my computer and Audacity. Later I will compare the computer measurements against my Chrony.
* Velocity measured at my normal 34 inches draw.

Further testing will be with 1842 because that is what I have.

Now I'm going outside to make some Chrony measurements.


Henry, what are the length of the tubes per side that are being tested?

#8 Performance Catapults

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Posted 25 December 2011 - 08:20 PM

...The real kicker is that the tubes are so easy to cut and change not to mention cheap(if you're just changing the single strand component).


...and, they are quiet.

#9 NaturalFork

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Posted 25 December 2011 - 08:27 PM

Those tubes are super fast. Getting that kind of FPS with such little effort makes them extremely worthwhile. We all appreciate your findings Henry!

#10 Henry the Hermit

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Posted 26 December 2011 - 07:31 AM

I've owned a Dankung Jungle Hunter II for more than a year. Right up front, I'll say I don't like the Dankung, but I do like the thin Chinese tubes. I plan to test a variety of configurations, and will use the Dankung because of the ease of changing tubes. To kick things off, here are the results I got from the original OEM bandset, which I assume were 1745.

Pull weight at 30 inches - 19 pounds
Velocity -
.375 lead ball (75 grains) - 192 fps avg 5 shots
.429 lead ball (115) grains - 182 fps avg 5 shots
.495 lead ball (175 grains) - 161 fps avg 5 shots
Note: all measurements were made with my computer and Audacity. Later I will compare the computer measurements against my Chrony.
* Velocity measured at my normal 34 inches draw.

Further testing will be with 1842 because that is what I have.

Now I'm going outside to make some Chrony measurements.


Henry, what are the length of the tubes per side that are being tested?


The double set is 7 inches, the "single" (more about its construction later) is 7.5. That is one of the variables I intend to explore. What is the optimum length for me? Once I determine that, we should be able to take a person's draw length and calculate the optimum for him/her.

#11 Henry the Hermit

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Posted 26 December 2011 - 08:48 AM

Yes indeed, they are quiet, and handslap is non-existant, even with .25 steel.

This morning I will be trying .177 BBs, but have to make an ultralight pouch first. My theory, which may be wacko (we shall see), is that if we reduce the weight of the projectile and pouch as much as possible, we can then measure how fast the bands are capable of retracting, and then know the absolute maximum speed of those bands.

OK, here are my results with the looped singles. First a picture of the bands.

looped-single-01.jpg

The loops measure 2.5 inches (6.35 cm) and the single portion is 5.0 inches (12.7 cm). The pull weight is 8.9 pounds at 32 inches. This is the first round. I have since achieved higher velocities by increasing my draw length. (See post above)

Velocities

.25 cal (6.35mm) steel - 282.8 fps - 2.88 lbs/ft energy.
.304 lead (7.7mm) - 255 fps - 6.0 lbs/ft energy *
.363 lead (9.2mm) - 211.4 - 7.04 lbs/ft energy *
.429 LEAD (10.9MM) - 177.54 - 8.18 lbs/ft **

* These two rounds were real eye openers. Not only is the velocity with .363 almost exactly the same as with the double set (212.4), the .304 is actually faster with the single bands, at roughly half the draw weight. (8.9 vs 15.8)
** The bands are obviously overloaded at this projectile weight, losing more than 20 fps to the double set. Even so, the higher energy level indicates that more speed can be achieved with the lighter projectiles. If my theory is correct, we should be able to get close to 300 fps with .304 lead and somewhat over that with .25 steel.

I'm going to bite the bullet and pay the price for 70 3/8 steel balls, since that is what almost everyone uses. Why don't you guys all switch to lead and save me 5 bucks? :)

#12 Performance Catapults

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Posted 26 December 2011 - 09:11 AM

The double set is 7 inches... That is one of the variables I intend to explore. What is the optimum length for me? Once I determine that, we should be able to take a person's draw length and calculate the optimum for him/her.


The fastest set I am offering at this point, the GT1842, is 7.25". Reason being, I didn't want anyone to damage their tendons. The GT1842 compares in resistence to the Tex Shooter, Express Double Flats, that I was shooting for the past few years. The pull is slightly heavier, but not so much that it is uncomfortable. Remember, I had stage 3 trigger thumb surgery, so if it was uncomfortable to shoot, I wasn't going to continue.

So, what a coincidence that our band measurements are so close. Some shooters will be able to handle the extra pull weight of 7". My draw is 30", and the GT1842 allows me to shoot comfortably for extended periods, without sacrificing survival saving, kinetic energy.

Edited by Performance Catapults, 26 December 2011 - 09:11 AM.


#13 AZshooter

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Posted 26 December 2011 - 09:46 AM

Thanks for taking the time to do the tests, Henry....I like the idea of the single tube with short loop at the fork end to help create a double tapered effect...What would be the best way to tie off the short loop?...constrictor knot...small piece of 1745 tubing...?

#14 LVO

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Posted 26 December 2011 - 11:37 AM

So, Henry this is all using a Dankung? We could expect same speeds using that setup with one of Jim's Performance units, or Bill Hays universal fork setup. Sorry for the newbie question, I'm just trying to get easiest draw to send rounds at about 225 fps.
Appreciate your help.

#15 Henry the Hermit

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Posted 26 December 2011 - 11:49 AM

"So, what a coincidence that our band measurements are so close."

Great minds think alike!

"What would be the best way to tie off the short loop?"

I use black waxed string that I buy from my local leather shop. It's roughly the same diameter as the cotton kite string I used to buy, but much stronger.

Now for the good news.

I did it!!!

chrony-300-01.jpg

And here are the bands I used. Length of one side 6.5 inches. The loop is just long enough to fit well on the Dankung. BTW, with the amount of shooting I'm doing, the Dankung is just too uncomfortable, so all future tests will be with Mr. Stubby. I've found no difference in performance but a huge difference in comfort.

looped-single-300fps.jpg

Now for some BBs.

#16 Charles

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Posted 26 December 2011 - 11:54 AM

Those are great results. What temperature were you shooting at, Henry?

Cheers ....... Charles

#17 Henry the Hermit

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Posted 26 December 2011 - 11:54 AM

So, Henry this is all using a Dankung? We could expect same speeds using that setup with one of Jim's Performance units, or Bill Hays universal fork setup. Sorry for the newbie question, I'm just trying to get easiest draw to send rounds at about 225 fps.
Appreciate your help.


You can use these bands on any frame you can fit them to. As I noted in my last post, I'm retiring the Dankung because I don't like shooting it. I've seen no difference in speed between it and Mr. Stubby.

http://slingshotforu...4559-mr-stubby/

#18 Henry the Hermit

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Posted 26 December 2011 - 12:54 PM

Those are great results. What temperature were you shooting at, Henry?

Cheers ....... Charles


It's 28 C outside right now, Charles. My heartfelt condolences to those of you who are cold. :)

#19 Charles

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Posted 26 December 2011 - 02:06 PM

Those are great results. What temperature were you shooting at, Henry?

Cheers ....... Charles


It's 28 C outside right now, Charles. My heartfelt condolences to those of you who are cold. :)


It is 5 C here now in Victoria. I am wondering how much of a difference the temperature will make with the tubes ... I know it can have a serious effect on bands. Anyway, I have just ordered a bunch of 1842 tubes from Dankung ... gonna give that stuff a try. High velocity with relatively light pull is a boon for those of us with arthritis.

Cheers ....... Charles

#20 NaturalFork

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Posted 26 December 2011 - 02:11 PM

With these speeds it makes me wonder why I continue to cut flats ...




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